Apparatus and method for fine blanking of parts

ABSTRACT

A fine-blanking die for mounting on a conventional punch press actuating device to punch out characterized shaped precisely finished parts e.g., gear blanks and gear blank segments from a sheet or strip material, so that these parts will have machinefinished edges and be of uniform thickness by providing an annular recessed wall surface in a portion of the die that is immediately adjacent and which extend outwardly of its cutting edge so that the scrapped metal in the sheet that surrounds the part being punched out can flow outwardly into the recessed portion of the die and thereby eliminate the undesired fractures rounded edges, burrs and other irregularly shaped surfaces that have heretofore been experienced from being formed in the outer periphery of the punched out part.

llnited States Patent Hanas 5] Jan. 18, 1972 [54] APPARATUS AND METHOD FOR FINE BLANKING OF PARTS [72] Inventor: Walter E. l-lanas, Roslyn, Pa.

[73] Assignee: Honeywell Inc., Minneapolis, Minn.

[22] Filed: Sept. 24, 1969 [21] Appl. No.: 860,761

[52] US. Cl ..72/329, 72/336, 83/164 [51] Int. Cl. 321d 31/02, B2ld 28/00, B2ld 7/06 [58] Field ofSearch .L ..72/333, 336, 329; 83/164 Primary Examiner-Charles W. Lanham Assistant Examiner-Robert M. Rogers Attomey-Arthur H. Swanson, Lockwood D. Burton and John Shaw Stevenson [5 7] ABSTRACT A fine-blanking die for mounting on a conventional punch press actuating device to punch out characterized shaped precisely finished parts e.g., gear blanks and gear blank segments from a sheet or strip material, so that these parts will have machine-finished edges and be of uniform thickness by providing an annular recessed wall surface in a portion of the die that is immediately adjacent and which extend outwardly of its cutting edge so that the scrapped metal in the sheet that surrounds the part being punched out can flow outwardly into the recessed portion of the die and thereby eliminate the undesired fractures rounded edges, burrs and other irregularly shaped surfaces that have heretofore been experienced from being formed in the outer periphery of the punched out part.

13 Claims, 6 Drawing Figures PATENTED JMI i 8 B72 ggc SHEET 2 BF 2 mm 09 mm mm ow k g No INVENTOR. WALTER E. HANAS AGENT.

APPARATUS AND METHOD FOR FINE BLANKING OF PARTS It is an object of the present invention to provide a die for precisely blanking out parts that have as fine a uniform outside dimension as that produced by machining.

Poor, partially cracked finishes have heretofore been experienced on the external peripheral surfaces of parts which have been produced by conventional blanking dies.

Experimentation has shown that the aforementioned irregular peripheral surfaces are caused by two forces, namely, a first force resulting from the downward pressure of the punch that-acts on the upper die portion as the cutting edge formed therein is employed to press a part from a sheet of metallic or nonmetallic material and a second force resulting from the opposing pressure providing by the bottom die portion. These opposing pressures tend to force the metal at the periphery of the part being blanked to flow toward its center so as to prevent the diameter of the blank from being enlarged and its thickness from being decreased.

Unsuccessful attempts have been made to eliminate the aforementioned rim-cracking problem by constructing fine blanking dies that allow metal to flow readily from the part that is to be produced as it is being punched out of the sheet in order to relieve the material forming the peripheral surface of the part and thereby obtain a less irregular surface on its outer periphery.

Although a slightly less cracked outer peripheral surface has been obtained by this last mentioned technique it has been found that this kind of fine blanking operation, in which the material flows away from the outer periphery of the disc part, will cause undesired die roll over, or, in other words, a loss of material in the area of the part forming its periphery as well as in a wide band portion of the part extending radially inward from its periphery. This deformation at the outer peripheral portion of the part therefore provides an unsatisfactory blanking surface on which teeth of the same thickness as the remaining inner portion of the part can be produced by hobbing.

Furthermore, when a series of the aforementioned blanks that are deformed at their peripheral portion are stacked together for hobbing the strips of metal cuttings which are removed from the outer blank surfaces will drop into the openings formed by each of the thin portions that are adjacent the outer peripheral surface of the blanks. Accumulation of gear cuttings in the aforementioned manner will require additional costly manufacturing expense because these gear parts when finished have to be cleaned and deburred.

When teeth are cut in a stack of blanks that are of uniform thickness at their peripheral and central portions, which is possible with the unique die provided herein, a milling cutter can force the cuttings that are being removed from the outer periphery of the successively aligned cut teeth across the periphery of all of the blanks and therefore will not allow the sharp edges of any of the cuttings to be brought into contact with the blanks during the aforementioned gear-cutting operation. It is therefore desirable to provide gear blank parts that will be of uniform thickness so as to avoid the aforementioned cleaning and deburring operations.

It is therefore an object of the present invention to provide a solution that eliminates the aforementioned problem by employing an annular recess area in a die immediately adjacent the cutting edge of the die into which material that is being removed about the peripheral surface of the part can flow in an outward direction so that the previously mentioned pressures will not be allowed to destroy the finish being formed on the aforementioned peripheral portion of the blanked out part.

It is another object of the present invention to provide a die of the aforementioned type that will in one punch press operation provide a smooth precise machine finish on the outer peripheral surface of a characterized shaped part, such as a disc, and which will therefore eliminate the previously mentioned costly drilling, milling, grinding and tumbling operations that have heretofore been required.

It is another object of the present invention to provide a rod shape piercing punch that has a concave surface in one end terminating in a circular cutting edge for effecting the removal of a scrap plug between two flat surfaces of a part.

It is still another object of the invention to employ a piercing punch of the aforementioned type that can be employed to punch out a scrap plug from an inner portion of a part while the previously mentioned blanking operation is taking place on the outer peripheral portion of the part.

It is an object of the present invention to disclose a blanking and a piercing punch of the aforementioned type that provides fine finished blanking and/or piercing of characterized shaped parts such as a gear segment, a ring-shaped plate, a disc or a gear blank from a strip or sheet of metallic or nonmetallic material.

A better understanding of the invention may be had from the following detailed description when read in connection with the accompanying drawings in which:

FIG. 1 is a partial cross-sectional view of the unique die when the press is in an open position;

FIG. 2 is a cross-sectional view of the die parts when the ram of the press has moved the upper die into pressing contact with the sheet to be blanked;

FIG. 3 is a view of the die during a blanking operation and shows how the material in the waste portion of the sheet immediately adjacent the cutting edge of the die is being moved upward into the annular grooved out surface in the top portion of the die and how a scrap plug is being removed by the unique concave piercing punch;

FIG. 4 is a cross section of the die after the diecutting cutting operation has been completed and the ram of the press has reached the bottom of its stroke.

FIG. 5 is a view of the die as it is moved in an upward direction away from the position shown in FIG. 4 with the characterized blanked out part, such as a disc, that is shown retained therein; and further shows how the knockout pins of the press are actuated by a knockout rod.

FIG. 6 is a view showing how the aforementioned blanked out part is autbmatically ejected from the die as it is returned to the position in FIG. 1 and further shows the distortion that occurs at the rim of the wall forming the punched out wall in the piece of scrap material that remains after the aforementioned die blanking and piercing operation.

The unique fine-blanking die 10 shown in FIGS. l-6 is comprised of a stationary blanking punch part 12 forming a first die part, and a second or upper die part 14. The upper die part 14 is, as shown in detail in FIG. 5, comprised of a die block 16, a punch pad 18 and a backing plate 20 that are mounted as a unitary part by means of connecting bolts, not shown, to the punchholder 22 for vertical up and down movement therewith by means of an actuating ram portion of a conventional punch press.

The punchholder 22 in turn has annular walls 24, 26 forming passageways for accommodating up and down movement of the knockout rod 28 that is mounted therein. A conventional die spring unit 30 containing a plurality of coils is shown surrounding the knockout rod 28 and within the confines of the annular wall 26. The coils of this die spring unit extends in a vertical direction between a protruding inner upper wall surface 32 of the punchholder 22 and a round-shaped knockout plate 34 that in turn is mounted for vertical movement with the inner circular wall 36 of the punchholder.

Parts 18-20 which form two of the three upper portions 14 of the die 10 have a suitable number of aligned cylindrical wall surfaces such as the two wall surfaces 38, 40; 42, 44, that form apertures therein for accommodating the vertical up and down sliding movement of conventional knockout pins 46, 48.

The upper ends of the knockout pins 46, 48 are retained in contact with the underside surface of the knockout plate 34 and the lower end of these pins 46, 48 are retained in contact with the upper surface of the cylindrically shaped knockout 50 as the result of the force that the spring 30 is continuously allowed to exert in a downward direction by way of the knockout plate 34 on these pins 46, 48.

The cylindrically shaped knockout 50 has cylindrically shaped peripheral surfaces 52, 54 that are mounted for sliding movement in associated cylindrically shaped wall portions 56, 58 which form two apertures in the die block 16 as shown.

The face of the die block 16 is shown having an annular slotted out portion 60 of an irregular V-shaped cross section and formed to provide a suitable shear-cutting angle e.g., l2 which will depend on the nature of the material to be punched.

The punch part 12 forming the first lower portion of the die 10 has a precisely machined upper cylindrical outer surface 62 at its upper end and a lower end portion 64 that is fixedly connected by a suitable connecting means, not shown, to the lower stationary shoe 66 ofa conventional press.

A stripper 68 which forms a support plate for the strip material 70 to be punched is shown having a wall 72 that forms a cylindrical passageway therein for sliding it in an up and down direction along the surface 62 of the punch part 12 ofthe fine-blanking die 10.

FIG. shows that the stripper 68 is supported on a suitable number of coil springs, for example, springs 74, 76 which extend between the underside of the stripper plate 68 and the lower die shoe 66. The stripper 68 which is of a plate-shaped construction is prevented from moving in an upward direction due to the force of the spring 74, 76 acting thereon by means of a suitable number of stripper bolts one such bolt 80 of which is shown by way ofillustration in FIG. 5.

Each of these bolts are threadedly connected at 82, in the same manner as that shown for bolt 80, at their upper end with the stripper 68 and as having a head portion 83 in fixed relation with respect to the lower shoe 66 in the manner shown in FIG. 5.

As illustrated by bolt 80 in FIG. 5 it can be seen that rotation of each of the aforementioned bolts can thus place the stripper plate 68 in a ready to punch position as shown for example in FIG. 1. In this FIG. 1 position the bottom of the strip of material 70 to be punched, the top surface of the punch part 12 and the stripper 68 are all at the same level.

When a die-blanking operation is to be performed an actuating ram means associated with a conventional press, not shown, will move the upper die portion 14 and parts associated therewith from its FIG. 1 position to the position of the die shown in FIG. 2 in which the lower face surface of the die block 16 and a knockout 50 will be brought into pressed physical surface to surface contact with the strip material 70 to be blanked.

While the pressure of the knockout pins 46, 48 cause the strip 70 to be sandwiched in an immovable relationship between the lower surface of the knockout 50 and the top sur face of the blanking punch part 12, the lower annular sharp cutting edge 84 on the lower end of the die block 16 that extends directly into the annular recess 60 begins to cut the scrap of material surrounding the part 86 that is to be blanked out of the scrap piece and which will remain after this blanking operation is completed as shown in FIG. 3. As this blanking operation takes place scrap material 88 surrounding the part being blanked will flow in a radial outward direction away from the outer surface of the cutting edge 84 into the annular recess 60 as is best shown in FIGS. 3 and 4. This will enable a precisely finished smooth part 86 to be produced that has a machine finish and which is of uniform thickness. During the time the press actuating ram effects the aforementioned action the blanked out part 86 and the knockout 50 will be progressively forced by the downward movement of the die block 16 into the cylindrical wall portion 58 of this die block as shown in FIGS. 3 and 4.

Although the part 86 that is cut from the strip of material 70 is shown to be of a disc-shaped configuration it should be understood that shapes of plates other than disc-shaped plates could be readily produced by a die similar to that already described by merely employing the same type of cutting. edge 84 and a recess, like recess 60, extending directly in an outward direction away from this cutting edge 84 around the characterized part to be cut from the strip 70.

As soon as the die block 16 is moved in an upward direction away from its FIG. 4 position toward the position shown in FIG. 5 the coils in the die spring unit 30 will be allowed to expand to release the energy that they acquired and stored during the cutting of the part 86 from the strip of material 70 that took place during the compression of this die spring 30 while the blanking steps shown in FIGS. 3 and 4 were taking place.

The expansion of the spring will thus apply a downward force by way of the knockout plate 34, the knockout pins 44, 48 and the knockout 50 against the blanked out part 86 that is retained in the die block 16 and this action in turn will cause the downward ejection of the finished part 86 between the punch pad 18 and the backing plate 20 as shown in FIG. 6.

If it is desired to punch a hole in the blank part 86 being pressed out of the strip 70 the die can be supplied with a piercing punch 90. As shown in FIG. 5 this punch 90 has an upper enlarged head portion 92 and a rod-shaped shank portion 94 that is retained between the punched pad 18 and the backing plate 20 for movement with the upper die portion 14.

FIG. 5 also shows that the lower remaining portion of the rod-shaped portion 94 passes through the cylindrically shaped wall 96 in the knockout 50 so that this knockout can be slidably moved in a vertical up and down direction on the rod portion 94 of the punch 90.

A concave surface 98 is formed in the lower end of the rod 94 that terminates at the outer rim of the rod 94 in a sharp annular-shaped cutting edge 100.

A cylindrical wall portion 102 forms an opening in the central portion of the upper area of the punch part 12 of the die set 10.

A wall 104 of an inverted funnel-shaped configuration in punch part 12 and a cylindrical wall 106 in stationary shoe 66 is shown forming extensions of the cylindrical wall portion 102 and provide a passageway through which a scrap plug 108 to be punched from the part 86 can be removed.

It can be seen that as the piercing punch 90 pierces the strip 70 as shown in FIG. 3 it will cut away only that portion of the strip 70 that forms the scrap plug 108 without causing any material to flow from the remaining part 86. This is made possible because of the concave recess in the bottom of the piercing punch 90 which provides an area into which a flow of metal in the scrap being formed into the scrap plug 108 can flow in an upward direction as it is being severed by the cutting edge 100.

It has been found that if suitable die materials are selected for the aforementioned die 10 it is capable of producing uniform precisely finished parts throughout unusually long production runs before redressing of the die is necessary.

Iclaim:

1. An apparatus adapted for mounting on a punch press to cut a characterized shaped member of uniform thickness from sheet material without compressing the material forming the peripheral surface ofthe member, comprising a first stationary die portion positioned on an underside of the sheet, a second movable die portion located on the top side of said sheet material and mounted for movement toward said first die portion, said second die portion having a cutting edge on a peripheral portion thereof that is aligned with the peripheral portion of the characterized shaped member to be cut from the sheet material, a recess formed in the face of the second die extending outwardly and upwardly away from a peripheral face surface portion of its cutting edge to provide a space into which distorted portions of the sheet material surrounding said characterized shaped member can freely flow without distorting or cracking the peripheral edge surface of said member as said second die portion engages said sheet material during its movement toward the first die portion.

2. The apparatus as defined in claim 1, wherein the recess formed by the face of the second die is a surface whose cross section is of a notch-shaped configuration.

3. The apparatus as defined in claim 1, wherein the crosssectional face surface of the second die which forms said recess is of a substantially inverted V-shaped configuration in which a first elongated wall portion of the inverted V-shaped recess extends from the face of the second die portion at an acute angle into the second die portion and away from the cutting edge thereof, and a remaining shorter wall'portion of the Vshaped recess extends away from the apex of the inverted V-shaped recess and at an obtuse angle to its first wall portion.

4. The apparatus as defined in claim 1, wherein the recess formed by the face of the second die is a wall surface portion that extends in an annular direction immediately away from and about the cutting edge.

5. The apparatus as defined in claim 1, wherein the recess formed by the face of the second die is a wall surface portion that extends in an annular direction immediately away from and about the cutting edge and wherein one portion of the recess extends radially outward at an acute angle to a plane passing through the cutting edge of the second die portion.

6. The apparatus as defined in claim 1, wherein the recess -formed by the face of said second die has a wall surface portion extending at a substantially 12 shear angle away from the cutting edge.

7. The apparatus as defined in claim 1, wherein the recess provides an annular surface into which the scrap sheet material surrounding said characterized shaped member can flow in a radial upward direction to form a distorted ridge on the upper edge of the recessed wall of the scrap sheet material while said second die portion engages said sheet material dur ing movement of the second die portion toward the first die portion.

8. The apparatus as defined in claim 1, wherein a piercing member is located in said second mentioned die portion and is operably connected for movement therewith to remove an elongated slug of material from the center of the characterized shaped member while the second die portion is moved toward the first die portion.

9. The apparatus as defined in claim 1, wherein a piercing member is located in said second mentioned die portion and is operably connected for movement therewith to remove an elongated substantially cylindrical slug of material from the central portion of the characterized shaped member while the second die is moved toward the first die, the piercing member has a cutting edge for shearing a circular slug of scrap sheet material from said central portion of the characterized shaped member and wherein a recess portion in the piercing member extends from said last-mentioned cutting edge into said piercing member to provide a chamber into which said cylindrical slug of sheared scrap sheet material can flow.

10. The method of manufacturing a gear blank from sheet material comprising the joint steps of: shearing and ejecting a cylindrical scrap plug from the material to form an inner apertured wall portion of the gear blank while forming the outer periphery of the gear blank by shearing a portion of the sheet material that surrounds and is spaced outwardly from its inner wall portion by forcing the sheet material being sheared to flow in an outward direction without being compressed.

l l. The method of manufacturing characterized shaped parts from sheet material comprising the joint steps of shearing an outer peripheral portion of the sheet material that surrounds each part without compressing the peripheral surface of each part and forcing the material in the sheet material being separated from each of said parts that remains as scrap to flow in an outward direction away from each of said respective parts.

12. The method of manufacturing characterized shaped parts from sheet material comprising the joint steps of shearing an outer peripheral portion of the sheet material that surrounds each part and forcing the material in the sheet material being separated from each of said parts that remains as scrap to flow in an outward direction away from each of said respective parts whereby any tendency for compressive forces to be applied to the peripheral surface of each of said parts is substantially diminished.

13. An apparatus adapted for mounting on a punch press to cut a characterized shaped member of uniform thickness from sheet material, comprising a first stationary die portion positioned on an underside of the sheet, a second movable die portion located on the top side of said sheet material and mounted for movement toward said first die portion, said second die portion having a cutting edge on a peripheral portion thereof that is aligned with the peripheral portion of the characterized shaped member to be cut from the sheet material, a recess formed in the face of the second die extending outwardly and upwardly away from a peripheral face surface portion of its cutting edge to provide a space into which distorted portions of the sheet material surrounding said characterized shaped member can freely flow as said second die portion engages said sheet material during its movement toward the first die portion whereby any tendency for compressive forces to be applied to the peripheral surface of said member is substantially diminished and distortion or cracking of the peripheral edge surface of said member is avoided. 

1. An apparatus adapted for mounting on a punch press to cut a characterized shaped member of uniform thickness from sheet material without compressing the material forming the peripheral surface of the member, comprising a first stationary die portion positioned on an underside of the sheet, a second movable die portion located on the top side of said sheet material and mounted for movement toward said first die portion, said second die portion having a cutting edge on a peripheral portion thereof that is aligned with the peripheral portion of the characterized shaped member to be cut from the sheet material, a recess formed in the face of the second die extending outwardly and upwardly away from a peripheral face surface portion of its cutting edge to provide a space into which distorted portions of the sheet material surrounding said characterized shaped member can freely flow without distorting or cracking the peripheral edge surface of said member as said second die portion engages said sheet material during its movement toward the first die portion.
 2. The apparatus as defined in claim 1, wherein the recess formed by the face of the second die is a surface whose cross section is of a notch-shaped configuration.
 3. The apparatus as defined in claim 1, wherein the cross-sectional face surface of the second die which forms said recess is of a substantially inverted V-shaped configuration in which a first elongated wall portion of the inverted V-shaped recess extends from the face of the second die portion at an acute angle into the second die portion and away from the cutting edge thereof, and a remaining shorter wall portion of the V-shaped recess extends away from the apex of the inverted V-shaped recess and at an obtuse angle to its first wall portion.
 4. The apparatus as defined in claim 1, wherein the recess formed by the face of the second die is a wall surface portion that extends in an annular direction immediately away from and about the cutting edge.
 5. The apparatus as defined in claim 1, wherein the recess formed by the face of the second die is a wall surface portion that extends in an annular direction immediately away from and about the cutting edge and wherein one portion of the recess extends radially outward at an acute angle to a plane passing through the cutting edge of the second die portion.
 6. The apparatus as defined in claim 1, wherein the recess formed by the face of said second die has a wall surface portion extending at a substantially 12* shear angle away from the cutting edge.
 7. The apparatus as defined in claim 1, wherein the recess provides an annular surface into which the scrap sheet material surrounding said characterized shaped member can flow in a radial upward direction to form a distorted ridge on the upper edge of the recessed wall of the scrap sheet material while said second die portion engages said sheet material during movement of the second die portion toward the first die portion.
 8. The apparatus as defined in claim 1, wherein a piercing member is located in said second mentioned die portion and is operably connected for movement therewith to remove an elongated slug of material from the center of the characterized shaped member while the second die portion is moved toward the first die portion.
 9. The apparatus as defined in claim 1, wherEin a piercing member is located in said second mentioned die portion and is operably connected for movement therewith to remove an elongated substantially cylindrical slug of material from the central portion of the characterized shaped member while the second die is moved toward the first die, the piercing member has a cutting edge for shearing a circular slug of scrap sheet material from said central portion of the characterized shaped member and wherein a recess portion in the piercing member extends from said last-mentioned cutting edge into said piercing member to provide a chamber into which said cylindrical slug of sheared scrap sheet material can flow.
 10. The method of manufacturing a gear blank from sheet material comprising the joint steps of: shearing and ejecting a cylindrical scrap plug from the material to form an inner apertured wall portion of the gear blank while forming the outer periphery of the gear blank by shearing a portion of the sheet material that surrounds and is spaced outwardly from its inner wall portion by forcing the sheet material being sheared to flow in an outward direction without being compressed.
 11. The method of manufacturing characterized shaped parts from sheet material comprising the joint steps of shearing an outer peripheral portion of the sheet material that surrounds each part without compressing the peripheral surface of each part and forcing the material in the sheet material being separated from each of said parts that remains as scrap to flow in an outward direction away from each of said respective parts.
 12. The method of manufacturing characterized shaped parts from sheet material comprising the joint steps of shearing an outer peripheral portion of the sheet material that surrounds each part and forcing the material in the sheet material being separated from each of said parts that remains as scrap to flow in an outward direction away from each of said respective parts whereby any tendency for compressive forces to be applied to the peripheral surface of each of said parts is substantially diminished.
 13. An apparatus adapted for mounting on a punch press to cut a characterized shaped member of uniform thickness from sheet material, comprising a first stationary die portion positioned on an underside of the sheet, a second movable die portion located on the top side of said sheet material and mounted for movement toward said first die portion, said second die portion having a cutting edge on a peripheral portion thereof that is aligned with the peripheral portion of the characterized shaped member to be cut from the sheet material, a recess formed in the face of the second die extending outwardly and upwardly away from a peripheral face surface portion of its cutting edge to provide a space into which distorted portions of the sheet material surrounding said characterized shaped member can freely flow as said second die portion engages said sheet material during its movement toward the first die portion whereby any tendency for compressive forces to be applied to the peripheral surface of said member is substantially diminished and distortion or cracking of the peripheral edge surface of said member is avoided. 